This application claims benefit of Japanese Application No. 2001-390363 filed in Japan on Dec. 21, 2001, and Japanese Application No. 2002-339716 filed in Japan on Nov. 22, 2002, the contents of which are incorporated by this reference.
1. Field of the Invention
The present invention relates to a fixing structure of a signal cable and, more particularly, to a fixing structure of a signal cable of an endoscope apparatus having a feature at the structure of a connector connected to a camera head.
2. Related Art Statement
An outer-coating layer of a cable preferably comprises a material with the inflectivity and softness in view of the operability. A product corresponding to the autoclave sterilization increasingly-uses the outer-coating containing silicon in consideration of the heat resistance. The thickness of the outer-coating layer is made thicker in accordance with the required product specification, giving the priority to the durability, or is made thinner, giving the priority to the outer diameter. However, when the outer-coating layer contains a material which is relatively soft and is easily split, a proper cable fixing method should be selected depending on the situation.
Then, Japanese Unexamined Patent Application Publication No. 5-293078 discloses a method for fixing a cable by fixing a tube member into which the cable is inserted. Further, Japanese Unexamined Patent Application Publication No. 2000-237128 discloses a method for fixing a cable by applying force in the direction for shearing the cable.
The present invention is devised in view of the above situations, and it is an object of the present invention to provide a fixing structure of a signal cable, which is capable of improving the tolerance for pulling out the cable from a main body portion or a connector portion of a probe portion in a medical device irrespective of the thickness of an outer coating when the outer coating contains a relatively soft material.
According to the present invention, a fixing structure of a signal cable comprises: a first tube member for inserting a signal line for transmitting a signal in the signal cable coated sequentially by a conductive shielding layer and a soft outer-coating layer, coated with the shielding layer and intervening between the signal line and the shielding layer; a second tube member having a step portion for forming an inner-diameter portion smaller than an outer diameter of the coated portion of the shielding layer so as to be engaged with the coated portion of the shielding layer which coats the first tube member, intervening between the shielding layer and the outer-coating layer so that the shielding layer can be sandwiched between the first tube member and the step portion; and a third tube member having a projected portion with an inner diameter smaller than an outer diameter of a coated portion of the outer-coating layer so as to be engaged with the coated portion of the outer-coating layer which coats the second tube member, covering the coated portion of the outer-coating layer so that the outer-coating layer can be sandwiched between the second tube member and the projected portion, wherein an end portion of the signal cable is fixed to a predetermined fixed target.
Other features and benefits of the present invention will apparently be understood by the following description.